--- a
+++ b/baselines/common/atari_wrappers.py
@@ -0,0 +1,235 @@
+import numpy as np
+from collections import deque
+import gym
+from gym import spaces
+import cv2
+cv2.ocl.setUseOpenCL(False)
+
+class NoopResetEnv(gym.Wrapper):
+    def __init__(self, env, noop_max=30):
+        """Sample initial states by taking random number of no-ops on reset.
+        No-op is assumed to be action 0.
+        """
+        gym.Wrapper.__init__(self, env)
+        self.noop_max = noop_max
+        self.override_num_noops = None
+        self.noop_action = 0
+        assert env.unwrapped.get_action_meanings()[0] == 'NOOP'
+
+    def reset(self, **kwargs):
+        """ Do no-op action for a number of steps in [1, noop_max]."""
+        self.env.reset(**kwargs)
+        if self.override_num_noops is not None:
+            noops = self.override_num_noops
+        else:
+            noops = self.unwrapped.np_random.randint(1, self.noop_max + 1) #pylint: disable=E1101
+        assert noops > 0
+        obs = None
+        for _ in range(noops):
+            obs, _, done, _ = self.env.step(self.noop_action)
+            if done:
+                obs = self.env.reset(**kwargs)
+        return obs
+
+    def step(self, ac):
+        return self.env.step(ac)
+
+class FireResetEnv(gym.Wrapper):
+    def __init__(self, env):
+        """Take action on reset for environments that are fixed until firing."""
+        gym.Wrapper.__init__(self, env)
+        assert env.unwrapped.get_action_meanings()[1] == 'FIRE'
+        assert len(env.unwrapped.get_action_meanings()) >= 3
+
+    def reset(self, **kwargs):
+        self.env.reset(**kwargs)
+        obs, _, done, _ = self.env.step(1)
+        if done:
+            self.env.reset(**kwargs)
+        obs, _, done, _ = self.env.step(2)
+        if done:
+            self.env.reset(**kwargs)
+        return obs
+
+    def step(self, ac):
+        return self.env.step(ac)
+
+class EpisodicLifeEnv(gym.Wrapper):
+    def __init__(self, env):
+        """Make end-of-life == end-of-episode, but only reset on true game over.
+        Done by DeepMind for the DQN and co. since it helps value estimation.
+        """
+        gym.Wrapper.__init__(self, env)
+        self.lives = 0
+        self.was_real_done  = True
+
+    def step(self, action):
+        obs, reward, done, info = self.env.step(action)
+        self.was_real_done = done
+        # check current lives, make loss of life terminal,
+        # then update lives to handle bonus lives
+        lives = self.env.unwrapped.ale.lives()
+        if lives < self.lives and lives > 0:
+            # for Qbert sometimes we stay in lives == 0 condtion for a few frames
+            # so its important to keep lives > 0, so that we only reset once
+            # the environment advertises done.
+            done = True
+        self.lives = lives
+        return obs, reward, done, info
+
+    def reset(self, **kwargs):
+        """Reset only when lives are exhausted.
+        This way all states are still reachable even though lives are episodic,
+        and the learner need not know about any of this behind-the-scenes.
+        """
+        if self.was_real_done:
+            obs = self.env.reset(**kwargs)
+        else:
+            # no-op step to advance from terminal/lost life state
+            obs, _, _, _ = self.env.step(0)
+        self.lives = self.env.unwrapped.ale.lives()
+        return obs
+
+class MaxAndSkipEnv(gym.Wrapper):
+    def __init__(self, env, skip=4):
+        """Return only every `skip`-th frame"""
+        gym.Wrapper.__init__(self, env)
+        # most recent raw observations (for max pooling across time steps)
+        self._obs_buffer = np.zeros((2,)+env.observation_space.shape, dtype=np.uint8)
+        self._skip       = skip
+
+    def step(self, action):
+        """Repeat action, sum reward, and max over last observations."""
+        total_reward = 0.0
+        done = None
+        for i in range(self._skip):
+            obs, reward, done, info = self.env.step(action)
+            if i == self._skip - 2: self._obs_buffer[0] = obs
+            if i == self._skip - 1: self._obs_buffer[1] = obs
+            total_reward += reward
+            if done:
+                break
+        # Note that the observation on the done=True frame
+        # doesn't matter
+        max_frame = self._obs_buffer.max(axis=0)
+
+        return max_frame, total_reward, done, info
+
+    def reset(self, **kwargs):
+        return self.env.reset(**kwargs)
+
+class ClipRewardEnv(gym.RewardWrapper):
+    def __init__(self, env):
+        gym.RewardWrapper.__init__(self, env)
+
+    def reward(self, reward):
+        """Bin reward to {+1, 0, -1} by its sign."""
+        return np.sign(reward)
+
+class WarpFrame(gym.ObservationWrapper):
+    def __init__(self, env):
+        """Warp frames to 84x84 as done in the Nature paper and later work."""
+        gym.ObservationWrapper.__init__(self, env)
+        self.width = 84
+        self.height = 84
+        self.observation_space = spaces.Box(low=0, high=255,
+            shape=(self.height, self.width, 1), dtype=np.uint8)
+
+    def observation(self, frame):
+        frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
+        frame = cv2.resize(frame, (self.width, self.height), interpolation=cv2.INTER_AREA)
+        return frame[:, :, None]
+
+class FrameStack(gym.Wrapper):
+    def __init__(self, env, k):
+        """Stack k last frames.
+
+        Returns lazy array, which is much more memory efficient.
+
+        See Also
+        --------
+        baselines.common.atari_wrappers.LazyFrames
+        """
+        gym.Wrapper.__init__(self, env)
+        self.k = k
+        self.frames = deque([], maxlen=k)
+        shp = env.observation_space.shape
+        self.observation_space = spaces.Box(low=0, high=255, shape=(shp[0], shp[1], shp[2] * k), dtype=np.uint8)
+
+    def reset(self):
+        ob = self.env.reset()
+        for _ in range(self.k):
+            self.frames.append(ob)
+        return self._get_ob()
+
+    def step(self, action):
+        ob, reward, done, info = self.env.step(action)
+        self.frames.append(ob)
+        return self._get_ob(), reward, done, info
+
+    def _get_ob(self):
+        assert len(self.frames) == self.k
+        return LazyFrames(list(self.frames))
+
+class ScaledFloatFrame(gym.ObservationWrapper):
+    def __init__(self, env):
+        gym.ObservationWrapper.__init__(self, env)
+
+    def observation(self, observation):
+        # careful! This undoes the memory optimization, use
+        # with smaller replay buffers only.
+        return np.array(observation).astype(np.float32) / 255.0
+
+class LazyFrames(object):
+    def __init__(self, frames):
+        """This object ensures that common frames between the observations are only stored once.
+        It exists purely to optimize memory usage which can be huge for DQN's 1M frames replay
+        buffers.
+
+        This object should only be converted to numpy array before being passed to the model.
+
+        You'd not believe how complex the previous solution was."""
+        self._frames = frames
+        self._out = None
+
+    def _force(self):
+        if self._out is None:
+            self._out = np.concatenate(self._frames, axis=2)
+            self._frames = None
+        return self._out
+
+    def __array__(self, dtype=None):
+        out = self._force()
+        if dtype is not None:
+            out = out.astype(dtype)
+        return out
+
+    def __len__(self):
+        return len(self._force())
+
+    def __getitem__(self, i):
+        return self._force()[i]
+
+def make_atari(env_id):
+    env = gym.make(env_id)
+    assert 'NoFrameskip' in env.spec.id
+    env = NoopResetEnv(env, noop_max=30)
+    env = MaxAndSkipEnv(env, skip=4)
+    return env
+
+def wrap_deepmind(env, episode_life=True, clip_rewards=True, frame_stack=False, scale=False):
+    """Configure environment for DeepMind-style Atari.
+    """
+    if episode_life:
+        env = EpisodicLifeEnv(env)
+    if 'FIRE' in env.unwrapped.get_action_meanings():
+        env = FireResetEnv(env)
+    env = WarpFrame(env)
+    if scale:
+        env = ScaledFloatFrame(env)
+    if clip_rewards:
+        env = ClipRewardEnv(env)
+    if frame_stack:
+        env = FrameStack(env, 4)
+    return env
+